Misconception number one: diet soda will make you gain or lose weight. You've probably heard it both ways and studies have shown both. Like a 2008 study at Purdue University, found that rats who were given the artificial sweetener saccharine gained more weight than rats who were given food with regular sugar. This was because the rats who ate saccharine tended to overeat later because their brain stopped associating sweetness with high calories.

As you'll remember from our episode on health food, there have also been a couple of long-term observational studies which showed that adults who drank diet soda are more likely to become obese. But there's no way to prove a connection just from an observational study, and --well known fact -- highly genetically engineered rats aren't people. There are also some new studies that are trying to find a connection between artificial sweeteners and metabolism, but nothing conclusive yet. So, studies like these lead to a lot of headlines about how diet soda will make you gain weight, but according to the analysis published in the September 2014 issue of the American Journal of Clinical Nutrition, we may be simplifying these findings when we say diet soda makes you gain weight. The reality is diet soda is just a part of the equation, someone's already dieting and forming healthy habits, soda alone isn't going to ruin that.

Misconception number 2: bottled water is safer than tap water. This obviously depends on where you live but in the U.S., bottled water companies actually have less regulations than city tap water/ For example, bottled water plants are required to test for coliform bacteria, which indicates sanitary quality, once a week. In big cities water's tested at least a hundred times a month. The test results for tap water must be reported to state and sometimes federal officials, but bottled water plants aren't required to report anything. You don't know what you're drinking.

Misconception number 3: milk increases phlegm. A 1990 study actually observed the relationship between phlegm and milk by infecting healthy adults with the rhinovirus infection, then monitoring their dairy product intake. The researchers found no statistically significant association between milk drinking and mucus production. Interestingly people who decreased their milk intake, when they had a cold, ended up having more cough and congestion symptoms.

Misconception number 4: eating Pop Rocks and drinking soda will kill you. In the seventies, an urban legend started that a boy named little Mikey from a Life cereal commercial died after eating Pop Rocks and drinking a Coke. The fact that Pop Rocks were pulled from shelves in the mid-eighties further encouraged this rumor. First, little Mikey's real name is John Gilchrist and he's still alive. And second, Pop Rocks disappeared for the boring reason that sales were decreasing, which was probably not helped by the rumor.

But Kraft soon bought the rights to them from General Foods and they were back.

Misconception number 5: Sports drinks are the best post-workout beverages. Sports drinks, like Gatorade, are pretty intense. Most of them contain potassium, sodium, and sugar, and sometimes after a workout it's good to replenish your body with all that stuff. But it's really only necessary if you just worked out very intensely for over an hour. For things like a jog on the treadmill or non-rigorous sports, a sports drink isn't necessary. Water is just fine. And, one study found that chocolate milk was better than Gatorade, it has carbs, nutrients and protein, and it's delicious. You can dip your Oreos in it, which is not recommended as a part of a healthy diet.

Misconception number 6: Drinking water clears toxins. It's actually kidneys that serve as a filter for the toxins in blood. Then we urinate those toxins out. But according to kidney expert Dr. Stanley Goldfarb from the University of Pennsylvania, drinking large amounts of water surprisingly tends to reduce kidney's ability to function as a filter. It's a subtle decline, but definite.

Misconception number 7: Fruit juice is good for you. Just like the diet soda issue, it's not that black and white, and of course the type of juice totally matters. But generally the sugar contents in many fruit juices are comparable to those in sodas. Also, a 2013 study conducted by the Harvard School of Public Health found that people who drink fruit juice three times a week had an 8% increase in diabetes risk. On the other hand, people who just ate fruit three times a week had a 2% decrease in risk. Experts recommend that if you enjoy drinking juice, do it in moderation.

Misconception number 8: Coke contains cocaine. When John Pemberton invented Coca Cola in the late 19th century, his recipe called for around 5 ounces of coca leaf in a gallon of syrup. Coca is what's used to make cocaine, and 5 ounces is kind of a lot. There are rumors that the company still uses this recipe today, but by 1902, there was significantly less cocaine in the drink. That's good. And by 1929, there was none at all. The company uses coca leaf extract, but it doesn't contain any cocaine.

Misconception number 9: Mountain Dew lowers sperm count. In the 90s many people thought that tartrazine, or the yellow dye in Mountain Dew, reduced sperm count. Some men started drinking a lot of Mountain Dew as a contraceptive, which doesn't work. In fact that may have had the opposite effect intended. According to Marc Goldstein, director of the Center for Male Reproductive Medicine and Microsurgery at Cornell University's medical school, if you take caffeine and mix it with sperm in a test tube it makes them swim better.

Misconception number 10: Soda can dissolve a tooth overnight. Many people will tell you that if you leave a tooth, nail, or coin in soda it will dissolve overnight. It's not true. Over time, it will dissolve a tooth thanks to its ingredients like citric acid and phosphoric acid, but orange juice will do the some thing. The acid content in both is low enough that we don't need to worry about destroying our teeth that are still in our mouths.

Thank you for watching Misconceptions on mental_floss on YouTube, which is made with the help of all of these nice people. If you have a topic for an upcoming Misconceptions episode that you'd like too see, please leave it in the comments. And I'll see you next week. Bye.